Members of a private security company pose on the rooftop of a house in Baghdad in 2007.Getty Images

In 2004, Sean McFate was sent to the African nation of Burundi to protect the country’s president from assassination, after word came down that a rebel group was advancing on his palace. Had the assassination occurred, the country would have likely descended into genocidal war.

In his new book, “The Modern Mercenary,” McFate writes that he accomplished his mission. He does not say how, but the “how” is less relevant than the “who.”

“The Modern Mercenary” by Sean McFate

McFate was not a member of the US (or any other) military, nor was he sent by the CIA or any covert ops organization. Instead, he was a contractor, employed by a corporation called DynCorp International. Some, as he notes, would call him a contractor; others, a mercenary.

But whatever the name, roles like McFate’s have become increasingly common over the past decade.

“Superpowers such as the United States cannot go to war without contractors in places like Iraq and Afghanistan, which was not the case even a generation ago,” he writes, also noting that “since 9/11, this industry has exploded from tens of millions to tens of billions of dollars in the chum slick of war contracts.” These contracts, he adds, can include “a license to kill under limited circumstances.”

Given this, he writes, we can expect the trend of military actions being executed by private concerns to only increase in the years to come.

While companies like Blackwater introduced Americans to the concept of having our wars fought in part by contractors working alongside our military, McFate makes the case that private-run warfare is quickly on its way to becoming the norm.

“‘Irregular’ warfare is [now] more regular than ‘regular’ warfare,” he writes, referring to war fought by contractors. “Militaries no longer battle other militaries, and nonstate actors now do the fighting and dying; an estimated 90 percent of casualties today are civilian . . . the number of internal conflicts has tripled, while the number of interstate wars has dwindled to nearly zero over the past 60 years.”

While making the case that contractors are a here-to-stay force, McFate points out that this has deep implications, both positive and negative, for modern warfare and international relations, and believes it’s important to consider both sides.

Having contractors fight wars produces a vast cost savings over full-time armies. The US Congressional Budget Office found that “the Army’s total cost of operating an infantry unit in Iraq was $110 million, while the same size unit from Blackwater was only $99 million.” The savings are even greater in peacetime, since “the cost of maintaining an army infantry unit at home is $60 million, whereas the cost of Blackwater is nothing, since [their] contract would be terminated.”

Contract warfare is literally a free market for force, where private armies and clients seek each other out, negotiate prices and wage wars for personal gain.

- Sean McFate, in 'The Modern Mercenary'

He also disputes the perception that “mercenaries are little more than murderous thugs,” believing that “the marketplace tends to discipline bad mercenaries.” As an example, when Blackwater contractors killed Iraqi civilians in 2007, it “saw its business with the United States plummet,” and its contract was not renewed in 2009. (Four former Blackwater guards were found guilty of various charges related to the incident this past October.)

The sacrifice has shifted as well. “In 2010,” he writes, “more contractors were killed than military personnel, marking the first time in history that corporate casualties outweighed military losses on US battlefields.”

That said, McFate does not gloss over the potential dangers inherent in what he sees as the emerging new world order.

Part of the problem is that the industry is barely regulated, allowing the potential for widespread fraud and abuse.

“The firms can be more opaque than US military or intelligence agencies, because they are not subject to the Freedom of Information Act or similar legislative tools that impose transparency,” he writes, adding that “even members of Congress do not have direct access to the contracts by which these firms are employed, even though Congress is writing the checks.”

It’s unsurprising, then, to learn that a congressional committee established to investigate accountability in conflict-zone contracting found that “at least $31 billion, and possibly as much as $60 billion, was lost to contract waste and fraud in Iraq and Afghanistan, much of which was avoidable.”

Iraqi and foreign mercenary members of a private security company in 2007, standing on the rooftop of a house in Baghdad.

Using private military forces also makes it easier to wage war, since anyone with enough money — including corporations and even private citizens — can do so. McFate cites examples such as Chevron and the mining company Freeport-McMoRan as companies that use private military for security at their mines or oil rigs, and says that “if money can buy firepower, then large corporations and ultrawealthy individuals will become a new kind of superpower.”

“A new type of war may emerge — contract warfare,” he writes. “Contract warfare is literally a free market for force, where private armies and clients seek each other out, negotiate prices and wage wars for personal gain.”

It’s imperative, then, that countries find a way to work with private military contractors that includes accountability, McFate observes that “already, private forces are manifesting across the five domains of war: land, sea, air, space and cyberspace,” ushering in a new, mysterious and potentially terrifying terrain of conflict.

“The future of private warfare seems bright,” he writes, “while the future of war looks perilous.”